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Re: IIc+ Power Supply mod.

Jorge Chamorro Bieling wrote:

Luke Forat <iceman@nospam.digidude.homeip.net> wrote:



  Jorge,
your speculations are correct. Modding from 220V input to 110V is possible with a wave doubler configuration (as you have noted, most non 
"autoregulating" PSUs have that switch which does exactly this) but the
contrary is a major problem and yes you risk a cap explosion and a junction
breakdown - some nasty fireworks and smoke. The best and quickest thing you
can do is get a 220 to 110V autotransformer with at least a 1 Amp rating on
the input - or - replace the PSU with a 220V one.

  Regards,

           Luke



Luke,

I think I'll try this BRUTE FORCE idea I've had:

What if I insert a 50w 110v zener in series with the bridge rectifier ?
The power supply is rated 36w, but that's maximum power. 
This switcher may have 80-90% efficiency ?
Then the zener will have to dissipate just a bit more than the IIc+... How much may be the average power consumption of the IIc+ ? 
The how big is the radiator that I need ?
What am I missing here ?


Although that would work in principle, it would, as you note,
*double* the amount of heat dissipated in the IIc+, with most
of it concentrated in the location of the zener.

Further, one of the failure modes of an overheated zener is
to short, which would take out a lot of the power supply.

The transformer is the best idea, and is fairly small, inexpensive,
and *reliable*.

-michael

Music synthesis for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

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